Dissertation Committee Chair: Steve Rolston, Trey Porto (co-chairs)
Committee:
Alan Migdall
Chandra Turpen
Tom Murphy (Dean’s Representative)
Abstract: This dissertation combines work from several disparate fields of research to explore the epistemic value of complexity and care in knowledge generation in physics. Complexity means intentionally constructing models that account for multiple interacting effects, yielding deeper insight and new research directions. Care means viewing physics as a fundamentally human endeavor and recognizing that the human aspects are as important as the technical aspects for rigorous and sustainable progress in physics.
The dissertation begins with experimental results using Rydberg atoms. Rydberg atoms, with their long lifetimes, sensitivity to electric fields, and strong interactions, have found use across atomic physics, from fundamental physics investigations to emerging quantum technologies. In this dissertation I describe efforts to optimize a Rydberg-ensemble single-photon source, which resulted in an accurate model of Rydberg spin-wave dephasing. I then show evidence of enhanced Rydberg interactions using microwave dressing. This is a first step toward many possible applications, including fully tunable interactions, the exploration of non-equilibrium phenomena, the generation of nonclassical states of light, and improved atom-photon entanglement for quantum networking.
The second part of this dissertation explores two photonic devices critical to quantum science and technology. First, we describe an algorithm for reconstructing the photon number distribution of light pulses using a single single-photon avalanche detector. We achieve high-fidelity reconstruction of both coherent and anti-bunched pulses whose duration and correlation timescales are both at least a few detector dead times in duration, and we explore the limits of the algorithm at high input photon rates. Second, we describe an \emph{ab initio} model of the random and time-varying birefringences of optical fibers. Environmentally induced drifts make this a serious challenge for polarization-encoded quantum networks, which is becoming crucial to understand as a new generation of quantum networks comes online. A first-principles model of the birefringences in fibers will allow for determinations about the suitability of installed fibers for quantum networking applications and for development of mitigation methods and compensation strategies.
In the final part of this dissertation, I describe the development and results of a national-scale study of physics and astronomy graduate student mental health. Mental health challenges in academia are well-documented, but the mental health of graduate students remains understudied, especially in physics and astronomy. Our sample reports clinical levels of anxiety and depression at 5-7 times the rate of the general population. Female and non-binary students in our sample report more symptoms of anxiety, depression, and impostor phenomenon than male students. Using structural equation modeling, we find that loneliness is an especially strong predictor of these mental health issues in our sample, and we clarify pathways by which advisors support their graduate students. Thus these results suggest specific ways that peers, faculty, and departments can support graduate student mental health.